The effect of organic loading rate on the aerobic granulation: the development of shear force theory

The effect of organic loading rate (OLR) on aerobic granulation was studied by adopting three column-shaped, sequential aerobic sludge blanket reactors (SASBR). The reactors had been fed with laboratory prepared, synthetic dextrose-nutrient broth substrate. Experimental results showed clearly that the formation, characteristics and stability of aerobic granules had a close relationship with the strength of OLR applied. Aerobic granules appeared firstly under the OLR of 4 kg COD x (m3 x day)(-1). The system stabilization was demonstrated by its little-changed amount and morphology of granules. The characteristics of the stabilized granules were: 5.4 mm in mean diameter, 1.29 in roundness, 118 mg O2 x (mg VSS x hr)(-1) in SPOUR. The respective biomass SVI was 50 mL x (g MLVSS)(-1) and the averaged COD removal rate was 95%. Under the OLR of 8 kg COD x (m3 x day)(-1), granules appeared two days later than those for 4 kg COD x (m3 x day)(-1) and they always coexisted with flocs. The formed granule bed was not as compact as that under 4 kg COD x (m3 x day)(-1). There were no granules formed under the OLR of 1 kg COD x (m3 x day)(-1). Instead, flocs with rather loose structure dominated reactor mixed-liquor. The respective SVI's were 65 and 138 mL x (g MLVSS)(-1) under OLR of 8 and 1 kg COD x (m3 x day)(-1). It was proposed that the growth and maintenance of aerobic granules follow the shear force balance theory. Under the OLR of 4 kg COD x (m3 x day)(-1), a balance was reached between the aeration shear force and organic loading rate. Under this favored condition aerobic granules formed quickly and, became stabilized with the experimental parameters remained unchanged.

Specific layers in aerobically grown microbial granules

AIMS

To determine the optimal size of aerobically grown granules for wastewater treatment by measuring specific layers within the granules.

METHODS AND RESULTS

A variety of biological layers were detected by oligonucleotide probes, specific fluorochromes, and fluorescent microspheres. The channels in the granule matrix penetrated to depths of 900 microm. A layer of obligate anaerobic bacteria was detected at a depth of 800 microm below the granule surface. Dead cells were also observed in the granule interior.

CONCLUSIONS

Aerobically grown granules contained layers of aerobic and anaerobic micro-organisms.

SIGNIFICANCE AND IMPACT OF THE STUDY

The optimal diameter of the aerobic granule is less than 1600 microm. This is twice the distance from the granule surface to the anaerobic layer. This approach can be used to optimize the thickness of other microbial aggregates such as flocs, colonies and biofilms.

Risk factors for male breast cancer in Canada, 1994-1998

Relatively little attention has been paid to the aetiology of male breast cancer and the current understanding of female breast cancer, primarily related to reproductive events, cannot be readily transferred to understanding the cancer in males. However, since male breast cancer occurs in the absence of factors related to childbearing and menstruation, its aetiology may provide special insights into the causes of breast cancer in women. We examined lifestyle risk factors for male breast cancer as part of a Canadian, multi-site, population-based, case-control study. Eighty-one newly diagnosed, histologically confirmed cases and 1905 male controls aged 42-74 were analysed using unconditional logistic regression. Increased risks were found for men with a mother or sister with breast cancer (adjusted odds ratio (OR) 3.65, 95% confidence interval (95% CI) 1.62-8.19). Higher physical activity levels (moderate, and strenuous recreational plus occupational) were associated with a decreased risk of male breast cancer (highest quartile, adjusted OR 0.48, 95% CI 0.26-0.91). Similarly, higher risks were associated with higher weight 2 years before interview (2.19, 95% CI 1.08-4.43), maximum weight (OR 2.66) and higher body mass index (OR 1.60). Higher vegetable consumption and coffee consumption were associated with decreased risk, whereas higher beta-carotene, vitamin E and calcium supplementation were associated with statistically significant increased risk. The small number of cases and multiple comparisons preclude strong conclusions, but our study is consistent with studies suggesting obesity and family history increase risk, and physical activity decreases risk of breast cancer.

HLA-A and HLA-B in Kenya, Africa: allele frequencies and identification of HLA-B*1567 and HLA-B*4426

HLA-A and HLA-B alleles of a population from Kenya, Africa were examined by sequencing exon 2 and exon 3 DNA and typing using a Taxonomy-based Sequence-analysis (TBSA) method. Extensive diversities were observed at both HLA-A and HLA-B loci in this population. Forty-one HLA-A alleles were identified from 159 unrelated individuals. The most frequently observed alleles were A*6802 (11.64%), A*02011/09 (9.75%), A*7401/02 (9.43%), A*3001 (7.86%), A*3002 (7.23%) and A*3601 (6.6%). Forty-nine HLA-B alleles were identified in 161 unrelated individuals, including two novel alleles, B*1567 and B*4426. The most frequently observed HLA-B alleles were B*5301 (9.01%), B*5801 (8.38%), B*4201 (7.76%), B*1503 (7.14%), B*1801 (6.21%), and B*5802 (5.90%). The most frequently observed HLA-A-B haplotypes were A*3601-B*5301 (3.55%) and A*3001-B*4201 (3.19%), followed by A*7401/02-B*5801 (2.84%), A*7401/02-B*5802 (2.84%) and A*02011/09-B*1503 (2.13%). Linkage disequilibrium and chi2 analysis showed the association of these HLA-A-B haplotypes at the antigen level to be significant. The frequencies of HLA-A and HLA-B alleles from the Kenyan population were compared with that of a population from Cameroon. The difference in allele and haplotype frequency distributions partly reflected the different ethnic composition of these two African populations.

[Administration of leukemic granulocyte colony-stimulating factor to donors: the changes in donor bone marrow cell composition and the transplantation outcome]

OBJECTIVE

To investigate the change of bone marrow cell composition the effect of graft on hemopoietic reconstitution and the incidence of acute graft-versus-host disease (aGVHD) with granulocyte colony-stimulating factor G-CSF administration to donors before marrow harvesting.

METHODS

Twenty-four patients with myeloid leukemia underwent allogeneic bone marrow transplantation. The donors of twelve patients (study group) were given G-CSF 250 microg/d for seven days prior to harvesting. The marrow cell composition, the outcome of subsequent engraftment and the occurrence of aGVHD were compared with those in twelve patients without G-CSF (control group).

RESULTS

The bone marrow stimulated by G-CSF yielded higher number of nucleated cells, CD34+ cells, CFU-GM and CFU-MK (P < 0.01). The number of T lymphocyte subsets in the graft stimulated with G-CSF was different from that in the control group. The number of CD4+ cells was decreased and that of CD8+ increased. The CD4+/CD8+ ratio was reduced markedly (P < 0.01). The change of CD34+, CD4+, CD8+ percentage and CFU-GM, CFU-MK proliferation in donor bone marrow with and without G-CSF was compared. The same characteristic change as above graft was observed. Hemopoietic reconstitution in the study group after allo-BMT was accelerated. In the study group the days of granulocyte count exceeding 0.5 x 10(9)/L and platelet count exceeding 20 x 10(9)/L were 16 days (range 11 - 23 days) and 17 days (range 14 - 25 days) (in the control group 20.5 day, range 14 - 29 days and 23 days, range 17 - 32 days P < 0.05). Grade II - IV aGVHD did not occur in patients of the study group but in 3 patients of the control group.

CONCLUSION

The bone marrow harvested from donor with G-CSF stimulation can accelerate hemopoietic recovery and decrease the incidence of severe aGVHD. The accelerated hematopoietic recovery is associated with increased number of CD34+, CFU-GM and CFU-MK in the graft.

Endoscopic mucosal resection with a cap-fitted endoscope for early gastric carcinoma with focal submucosal invasion in a patient with decompensated liver cirrhosis

Prognosis for patients with early gastric cancer who undergo gastric resection is far better than that for patients with advanced disease. However, patients with advanced liver cirrhosis may not be suitable for general anesthesia and major surgery. We used a less invasive endoscopic mucosal resection (EMR) with a cap-fitted endoscope to resect an early gastric cancer in a 58-year-old male with decompensated liver cirrhosis. Although postoperative pathology revealed that the tumor had focal invasion to the submucosa, the patient had an uneventful course and was well during 4 years' follow-up. This method may be effective for the treatment of early gastric cancer with focal submucosal invasion when patients are not suitable for major surgery.

Vascular endothelial growth factor isoforms display distinct activities in promoting tumor angiogenesis at different anatomic sites

The gene for the major angiogenic factor, vascular endothelial growth factor (VEGF), encodes several spliced isoforms. We reported previously that overexpression of two VEGF isoforms, VEGF(121) and VEGF(165), by human glioma U87 MG cells induced tumor-associated intracerebral hemorrhage, whereas expression of a third form, VEGF(189), did not cause vessel rupture. Here, we test whether these VEGF isoforms have distinct activities for enhancing vascularization and growth of gliomas in mice. U87 MG cells that overexpressed VEGF(165) or VEGF(189) grew more rapidly than the parental cells in both s.c. and intracranial (i.c.) locations. However, cells that overexpressed VEGF(121) only showed enhancement of i.c. tumor growth but had a minimal effect on s.c. glioma progression. At both anatomical sties, VEGF(165) and VEGF(189) strongly augmented neovascularization, whereas VEGF(121) only increased vessel density in brain tumors. In each type of glioma, expression of VEGF receptors -1 and -2 largely phenocopied the tumor vasculature, because increased VEGF/VEGF receptor-activated microvessel densities were strongly correlated with the angiogenicity and tumorigenicity elicited by the VEGF isoforms at both anatomical sites. One notable difference between the sites was the expression of vitronectin, a prototypic ligand of alpha(v)beta(3) and alpha(v)beta(5) integrins, detected in i.c. but not in s.c., gliomas. Endothelial cell migration stimulated by VEGF(121) was potentiated by vitronectin to a greater extent than that stimulated by VEGF(165). This data demonstrates that VEGF isoforms have distinct activities at different anatomical sites and suggest that the microenvironment of different tissues affects the function of VEGF isoforms.

[Clinical and pathological characteristics of heroin spongiform leukoencephalopathy in China]

OBJECTIVE

To observe the clinical, image and pathological characteristics of Heroin Spongiform Leukoencephalopathy(HSLE).

METHODS

Clinical, CT and MRI analysis of 28 cases, brain autopsies of 2 cases and brain biopsies of 8 cases with HE, Loyez and Congo Red staining and observation through electron microscope.

RESULTS

The clinic, image and pathologic characteristics of HSLE: (1) the history of inhalation of heated heroin vapor; (2) among 28 cases with HSLE, recurrence of HSLE was found in 17 cases during the abstinence, in 8 cases 1-2 month after abstinence, in 2 cases 4 month after abstinence and in 1 case after inhaling large amount of heroin; (3) the majority of cases were described with the acute onset characterized by cerebellar signs; (4) pyramidal tract lesion was frequently involved, but sensory system usually remained normal; (5) CSF test was normal; (6) CT and MRI revealed extensive symmetric white matter lesions in cerebra and cerebellum; (7) spongiform vacuoles degeneration of white matter was the main morphological change.

CONCLUSIONS

Spongiform leukoencephalopathy may be considered if a patient who had a history of inhaling heated heroin vapor showed acute cerebellar signs. Spongiform vacuoles degeneration of cerebral white matter was the main pathological change.

Early colonic carcinoma with extensive lymph node metastases: case report and review of literature

An 81-year-old woman had an early carcinoma invading focally into the upper submucosa of the middle-transverse colon, which was accompanied by extensive lymph node metastases and resulted in a poor prognosis. Although her tumor was small and flat, a rim of pale yellow-speckled mucosa adjacent to the tumor enabled its earlier detection. To further study the exceptional lymph node metastases we studied the expression of intestinal trefoil factor and sialyl Tn antigen immunohistochemically on the resected specimen. Their simultaneous expression in lymph node metastasis further supports the aggressive nature of this tumor.

Role for tissue factor pathway in murine model of vascular remodeling

Tissue factor (TF) is a low-molecular-weight glycoprotein that initiates the extrinsic clotting cascade and is considered a major regulator of arterial thrombogenicity. TF pathway inhibitor (TFPI) is a major physiological inhibitor of TF-initiated coagulation. The aim of this study was to define the complex interplay between TF and TFPI and the regulation of vascular thrombogenicity in a model of vascular remodeling. To determine the levels and pattern of vascular expression of TF and TFPI associated with vascular remodeling, a murine model of flow cessation was studied. TF activity of the arteries increased after ligation (P<0.05). Quantitative analysis of homogenates of remodeled carotid arteries revealed increased TF expression but unchanged TFPI expression compared with normal carotid arteries, resulting in enhanced TF activity. To determine the potential therapeutic role of TFPI in this thrombogenic state, mice were treated with intravascular adenoviral delivery of either murine TFPI (Ad-mTFPImyc) or a control adenovirus (Ad-DeltaE1). Overexpression of TFPI decreased vascular TF activity compared with viral control (P<0.01). Overexpression of TFPI inhibited neointimal formation (P=0.038), resulting in enhanced luminal area (P=0.001) 4 weeks after flow cessation. In this murine model of vascular remodeling, an imbalance between TF and TFPI expression is generated, resulting in increased TF activity. Overexpression of TFPI in this model inhibits vascular TF activity and results in attenuation of vascular remodeling associated with flow interruption.

Investigation of the extent of gastric metaplasia in the duodenal bulb by using methylene blue staining

BACKGROUND AND AIMS

The existence of gastric metaplasia (GM) of the duodenal mucosa has been considered to be highly related to the recurrence of duodenal ulcers (DU). The aims of this study are to evaluate the usefulness of methylene blue staining in the detection of GM, and to clarify the relationship between GM and the deformity of the duodenal bulb.

METHODS

Fifteen patients with healed DU and four patients with symptoms of dyspepsia without evidence of ulcers were enrolled into this endoscopic study. During each endoscopy, methylene blue was sprayed evenly on the duodenal bulb, and biopsies were taken from blue-stained and unstained areas. The existence and extent of GM were assessed histologically and grossly. The correlation between duodenal bulb deformity and the extent of GM was also studied.

RESULTS

The mean score of methylene blue non-staining (MBNS) was 0, 1.30 +/- 0.15, and 3.00 +/- 0.00 in group A (non-ulcer patients), group B (patients with healed DU and with normal-shaped bulb) and C (patients with healed DU and with deformed duodenal bulb), respectively; showing significant differences among the groups (P < 0.05 in each). Both the existence and the grading of GM were higher in unstained specimens than in blue-stained specimens (100 vs 16.6%, P < 0.0001 and 3.62 +/- 0.09 vs 0.19 +/- 0.06, P < 0.001, respectively).

CONCLUSIONS

Methylene blue non-staining can be applied to investigate the existence and extent of GM in the duodenal bulb accurately. The incidence of GM in the duodenal bulb was higher in patients with healed ulcers than in non-ulcer patients. Patients with deformed duodenal bulbs have a higher extent of GM than those without deformed duodenal bulbs.

[Intron 44 is not the most unstable intron in the "central deletion hot spot" of dystrophin gene]

OBJECTIVE

To understand the distributional characteristics of dystrophin gene deletion breakpoints in "central deletion hot spot" and analyze the instability of introns 44-51 after excluding the effect of intron's length.

METHODS

Fifty-nine Duchenne/Becker muscular dystrophy(DMD/BMD) patients were detected by polymerase chain reactions with the primers to amplify exons 44-52 of dystrophin gene. The amount of actual breakpoints, expected breakpoints according to its length, and the ratios of actual breakpoints to expected values(A/E) for introns 44-51 were calculated respectively.

RESULTS

In "central deletion hot spot", about 30.8% of breakpoints fell in intron 44, about 23.1%, 17.9%, 10.3%, 10.3% of breakpoints fell in introns 50,51, 45, 48, respectively. But the amount of actual breakpoints of intron 44 was less than that of expected breakpoints according to its length, the ratio of A/E was 0.7. The amount of actual breakpoints of introns 48, 50, 51, 45 were more than that of length expected value. The ratios of A/E were 2.7, 2.0, 1.9, 1.1, respectively.

CONCLUSION

Intron 44 is more stable than the whole molecular region of "central deletion hot spot". Introns 48, 50 and 51 are comparatively instable in "central deletion hot spot".

Overexpression of Hp95 induces G1 phase arrest in confluent HeLa cells

Xp95, a protein recently identified in Xenopus laevis, is potentially involved in progesterone-induced Xenopus oocyte maturation. In this study, we cloned a human homologue of Xp95, designated Hp95, and examined the effect of its overexpression on the growth properties of human malignant HeLa cells which have lost the contact inhibition of cell proliferation. We observed that although HeLa cells did not undergo G1 phase arrest at any stage after confluence, they were able to downregulate their G1 phase CDK activities in response to confluence. When Hp95 was overexpressed in HeLa cells by transfection with a constitutive or an inducible expression vector containing a full-length Hp95 transgene, HeLa cells became able to undergo G1 phase arrest and form a monolayer culture after confluence. However, the G1 phase CDK activities in these Hp95 overexpressing cells were not inhibited further as compared to control cells after confluence. These results indicate that the defects in HeLa cells that cause the loss of contact inhibition of cell proliferation are in components downstream of the G1 phase CDKs and that overexpression of Hp95 counteracts some of these defects.

Mining time dependency patterns in clinical pathways

Clinical pathways are widely adopted by many large hospitals around the world in order to provide high-quality patient treatment and reduce the length of hospital stay of each patient. The development of clinical pathways is a lengthy process, and may require the collaboration among physicians, nurses, and staffs in a hospital. However, the individual differences cause great variances in the execution of clinical pathways. It calls for a more dynamic and adaptive process to improve the performance of clinical pathways. This paper reports a data mining technique we have developed to discover the time dependency pattern of clinical pathways for managing brain stroke. The mining of time dependency pattern is to discover patterns of process execution sequences and to identify the dependent relation between activities in a majority of cases. By obtaining the time dependency patterns, we can predict the paths for new patients when he/she is admitted into a hospital; in turn, the health care procedure will be more effective and efficient.

Adjuvant sclerotherapy after ligation for the treatment of esophageal varices: a prospective, randomized long-term study

BACKGROUND

To assess the efficacy of adjuvant sclerotherapy after banding for the treatment of esophageal varices, a randomized trial was carried out of endoscopic variceal ligation (EVL) alone with sequential sclerotherapy versus sequential ligation-sclerotherapy (SLS) after banding with respect to variceal eradication, associated complications, and recurrence of varices.

METHODS

One hundred patients qualified for this study. Fourteen patients were not included for the following reasons: 6 chose not to participate, 4 had fundal varices, and 4 had some form of cancer. Of the remaining 86 patients in the study, 42 underwent EVL alone and the other 44 SLS. Variceal ligation was begun in the region of the gastroesophageal junction, with subsequent ligatures applied cephalad 3 to 5 cm; ligation was repeated every 2 weeks until variceal obliteration. For SLS, ligation was also begun in the region of the gastroesophageal junction and repeated until varices were reduced to F1 size. Subsequently, these patients underwent sclerotherapy with between 6 and 8 mL of sodium tetradecyl sulfate (free hand technique).

RESULTS

No significant differences were found between EVL alone and SLS with regard to variceal eradication, development of associated complications, and recurrent bleeding during a follow-up of 2 years. The probability of variceal recurrence requiring further treatment after 1 year was 14% for the SLS group and 26% for EVL group patients. Another year later, the probability of variceal recurrence was 24% and 45%, respectively, for the SLS and EVL groups.

CONCLUSIONS

Because a significantly lower rate of variceal recurrence was found for SLS patients, sequential sclerotherapy followed by ligation to eradicate those varices too small to easily band may be a better procedure.

Relationship of duodenal ulcer recurrence to gastric metaplasia of the duodenal mucosa and duodenal bulb deformity

BACKGROUND AND PURPOSE

This study investigated changes in the severity of gastric metaplasia (GM) of the duodenal mucosa before and after ulcer healing and Helicobacter pylori eradication. It also investigated whether deformity of the duodenal bulb affects the severity of GM and the likelihood of ulcer recurrence.

METHODS

Eleven patients were consecutively enrolled in this study. They all had duodenal ulcer(s) and H. pylori infection, for which they had received anti-H. pylori triple therapy during the active ulcer stage, and had all undergone serial endoscopic examinations during both the active ulcer and scarring ulcer stages, and at 1 year after ulcer healing. Duodenal biopsies were obtained at each endoscopy to identify the severity of GM. Duodenal ulcers were divided into three types by bulbar shape and GM was classified into four grades of severity.

RESULTS

All 11 patients had increased GM severity just after ulcer healing. The 1-year follow-up study revealed that the GM was unchanged in six of eight patients with grade 3 GM severity at the scarring stage, while in the other two it regressed to grade 1 or 2; these two patients suffered ulcer recurrence. A markedly deformed bulb (type III) was found in three patients, of whom two had ulcer recurrence.

CONCLUSION

Two characteristic conditions were found in patients with duodenal ulcer recurrence after H. pylori eradication: a markedly deformed bulb with grade 3 GM at the scarring stage, and a change in GM from high to low grade at or around the previous ulcer site after ulcer healing.

Factors influencing the induction of DT-diaphorase activity by 1,2-dithiole-3-thione in human tumor cell lines

NAD(P)H:(quinone acceptor)oxidoreductase (DT-diaphorase) is a two-electron reducing enzyme that activates bioreductive antitumor agents and is induced by a wide variety of compounds including 1,2-dithiole-3-thione (D3T). We investigated factors influencing DT-diaphorase induction in fourteen human tumor cell lines. Four cell lines had basal DT-diaphorase activity that was increased by D3T treatment (group A), six cell lines had basal DT-diaphorase activity but the activity was not increased by D3T (group B), and four cell lines had low enzyme activity without, or with, D3T (group C). Two cell lines in group A and two cell lines in group B had a C to T polymorphism at base 609 in the NQO(1), DT-diaphorase gene, in one allele, while all four cell lines in group C were homozygous mutants. The base 609 mutant NQO(1) gene produces a protein with little enzyme activity. In group A, D3T increased NQO(1) mRNA and wild-type protein, and also increased mutant protein in the two heterozygous cell lines. In group B, the inducer slightly increased NQO(1) mRNA, did not increase the wild-type protein, but did increase the mutant protein in the two heterozygous cell lines. In group C, D3T increased NQO(1) mRNA as well as its mutant enzyme product. Transfection of the mutant NQO(1) gene into cells with two wild-type alleles did not alter DT-diaphorase activity. The results suggest that the lack of induction of DT-diaphorase activity is transcriptional in nature, that basal and induced expression of DT-diaphorase are regulated independently, and that mutant NQO(1) does not act as a dominant-negative to suppress DT-diaphorase activity.

[Human cytomegalovirus inhibits the proliferation of CFU-MK in vitro]

OBJECTIVE

To investigate the effect of human cytomegalovirus (HCMV) on the proliferation of colony forming unit-megakaryocyte (CFU-MK).

METHODS

Semi-solid CFU-MK culture system was used to observe the effect of HCMV AD169 strain on CFU-MK growth of 20 cord blood samples. HCMV DNA and immediate early antigen (IEA) mRNA in CFU-MK were detected by in situ-polymerase chain reaction (IS-PCR) and reverse transcriptase-polymerase chain reaction (RT-PCR).

RESULTS

HCMV AD169 suppressed the differentiation and proliferation of CFU-MK in vitro significantly. The suppression was in a dose-dependent fashion. HCMV DNA was successfully detected in colony cells from viral infection group, and did the expression of HCMV IEA mRNA.

CONCLUSION

HCMV AD169 can directly infect megakaryocyte progenitor and suppress their proliferation and differentiation.

The sequence of the human genome

A 2.91-billion base pair (bp) consensus sequence of the euchromatic portion of the human genome was generated by the whole-genome shotgun sequencing method. The 14.8-billion bp DNA sequence was generated over 9 months from 27,271,853 high-quality sequence reads (5.11-fold coverage of the genome) from both ends of plasmid clones made from the DNA of five individuals. Two assembly strategies-a whole-genome assembly and a regional chromosome assembly-were used, each combining sequence data from Celera and the publicly funded genome effort. The public data were shredded into 550-bp segments to create a 2.9-fold coverage of those genome regions that had been sequenced, without including biases inherent in the cloning and assembly procedure used by the publicly funded group. This brought the effective coverage in the assemblies to eightfold, reducing the number and size of gaps in the final assembly over what would be obtained with 5.11-fold coverage. The two assembly strategies yielded very similar results that largely agree with independent mapping data. The assemblies effectively cover the euchromatic regions of the human chromosomes. More than 90% of the genome is in scaffold assemblies of 100,000 bp or more, and 25% of the genome is in scaffolds of 10 million bp or larger. Analysis of the genome sequence revealed 26,588 protein-encoding transcripts for which there was strong corroborating evidence and an additional approximately 12,000 computationally derived genes with mouse matches or other weak supporting evidence. Although gene-dense clusters are obvious, almost half the genes are dispersed in low G+C sequence separated by large tracts of apparently noncoding sequence. Only 1.1% of the genome is spanned by exons, whereas 24% is in introns, with 75% of the genome being intergenic DNA. Duplications of segmental blocks, ranging in size up to chromosomal lengths, are abundant throughout the genome and reveal a complex evolutionary history. Comparative genomic analysis indicates vertebrate expansions of genes associated with neuronal function, with tissue-specific developmental regulation, and with the hemostasis and immune systems. DNA sequence comparisons between the consensus sequence and publicly funded genome data provided locations of 2.1 million single-nucleotide polymorphisms (SNPs). A random pair of human haploid genomes differed at a rate of 1 bp per 1250 on average, but there was marked heterogeneity in the level of polymorphism across the genome. Less than 1% of all SNPs resulted in variation in proteins, but the task of determining which SNPs have functional consequences remains an open challenge.

Trifluoromethyl-containing 3-alkoxymethyl- and 3-aryloxymethyl-2-pyridinones are potent inhibitors of HIV-1 non-nucleoside reverse transcriptase

3-Alkoxymethyl- and 3-aryloxymethyl-2-pyridinones were synthesized and evaluated for activity as non-nucleoside reverse transcriptase inhibitors (NNRTIs) of HIV-1. It was found that several compounds were potent inhibitors of HIV-1 with the most potent compound 24 exhibiting an IC90 = 32 nM. Compound 24 also possessed a potent resistance profile as demonstrated by submicromolar IC90s against several clinically meaningful mutant virus strains.

Low incidence of severe aGVHD and accelerating hemopoietic reconstitution in allo-BMT using lenograstim stimulated BM cells

OBJECTIVES

To investigate the efficacy of accelerating hemopoietic reconstraction and reducing a graft versus host disease (GVHD) in Allo-BMT receiving lenograstim stimulated donor marrow and to assess the preliminary biological mechanism.

METHODS

The donors for thirty patients (study group) with leukemia were given lenograstim 3-4 micrograms.kg-1.d-1 for seven days prior to marrow harvest. The results of subsequent engraftment in the recipients was compared with fifteen donors without G-CSF (control group). Five donors themselves were studied to assess the effects of lenograstion on hematopoietic progenitor cells and lymphocyte subsets in BM.

RESULTS

The stimulated bone marrow contained a higher number of nucleated cells, CFU-GM and CD34+ cells (P < 0.01). The hematopoetic reconstitution was accelerated. Until granulocyte counts exceeded 0.5 x 10(9)/L and plalete counts exceeded 20 x 10(9)/L, the days were 16.7 +/- 3.2 and 18.4 +/- 3.0 days as compared with those of the control group (22.5 +/- 5.1 and 26.3 +/- 5.9 days respectively, P < 0.01). The incidence of grade II-IV aGVHD was very low, only one case with grade II aGVHD on the skin in the study group. Four out of fifteen patients (26.7%) in the control group had grade II-IV aGVHD (P < 0.05). The number of T lymphocyte subsets in the harvested BM stimulated by G-CSF changed. In comparison with the control group, CD4+ decreased and CD8+ increased significantly (P < 0.01). The changes of progenitor cells and T lymphocyte subsets in BM from pre- to post-G-CSF stimulation indicated that the percentage of CD4+ cells reduced (P < 0.05), that of CD8+ cells, and that of CD34+ increased (P < 0.01). The incidence of chronic GVHD and relapse of leukemia were not different significantly between both groups.

CONCLUSIONS

Allogenic bone marrow transplant (Allo-BMT) donors given G-CSF can accelerate engraftment and minimize the incidence of severe aGVHD. There is a trend in favour of improved transplant-related complications.

[Correlation between electroretinographic findings, clinical phenotypic and genotypic analysis in Duchenne and Becker muscular dystrophy]

OBJECTIVE

To explore the relationship between electrophysiological changes, clinical phenotype and genotype in Duchenne and Becker muscular dystrophy(DMD/BMD), to address the expression and roles of dystrophin and its isoforms on the retina, and to inquire into the molecular mechanism of the abnormal electroretinogram(ERG) on DMD/BMD patients with different genotype.

METHODS

Gene deletions were screened by multiplex DNA amplification with eleven primers on twenty-two consecutive patients with DMD and BMD, and then, the ERG was tested according to international ERG standard.

RESULTS

ERG phenotype was associated with the site of DMD gene defects rather than the severity of the phenotype. Patients with deletion in the central region of the gene had more severe changes in the scotopic ERG as compared to those with gene non-deletion.

CONCLUSION

The ERG genotype-phenotype correlation suggests that DP260 may play the most important role in the retinal neurotransmission.

3,3a-Dihydropyrano[4,3,2-de]quinazolin-2(1H)-ones are potent non-nucleoside reverse transcriptase inhibitors

A series of unique 3,3a-dihydropyrano[4,3,2-de]quinazolin-2(1H)-ones and a 2a,5-dihydro-2H-thieno[4,3,2-de]quinazo-line-4(3H)-thione were found to be HIV-1 non-nucleoside reverse transcriptase inhibitors. One of these compounds, as the racemate, possessed an IC90 = 4.6 nM against wild-type virus in a whole cell antiviral assay and had an IC90 = 76 and 897 nM against the clinically significant K103N and K103N/L100I mutant viruses, respectively.

Acrokeratosis paraneoplastica (Bazex syndrome) with adenocarcinoma of the colon: report of a case and review of the literature

Acrokeratosis paraneoplastica is a rare disease and is uncommon even in patients with upper aerodigestive tract cancer. We report a 63-year-old man with a 1-month history of numerous pruritic lesions and vesicles on both feet. Although he had received local therapy, progressive dense scale formation involving both palms and both soles was found. Colonoscopy was performed because of hematochezia, and it revealed an early colon cancer. After the resection of the cancer, the skin lesions began to fall off dramatically. To the best of our knowledge, there is no report of acrokeratosis paraneoplastica associated with colon cancer in the literature. This is the first case report of acrokeratosis paraneoplastica associated with early colon cancer.

[Changes of leukocyte rheologic characteristics and cell adhesion molecules in patients with multiple organ failure after severe trauma]

OBJECTIVE

To explore the changes of leukocyte rheologic characteristics and of cell adhesion molecule in patients with multiple organ failure (MOF) after severe trauma.

METHODS

By using the erythrocyte deformability apparatus, platelet and thrombus adhesion dual-purpose apparatus and enzyme-linked immunosorbent assay (ELISA), We measured the leukocyte deformability (LD), leukocyte adhesion function (LAF), leukocyte CD18 expression, soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule (sVCAM-1) concentration in 36 MOF patients, 31 trauma patients, and 35 to be controls.

RESULTS

The leukocyte filtration index (LFI), leukocyte adhesion rate (LAR), leukocyte CD18 expression, and sICAM-1 and sVCAM-1 concentration were significantly higher in MOF patients than in controls and trauma patients (F = 68.45 - 116.20, q = 12.161 - 21.374, P < 0.00), and the changes of these indicators in MOF deaths were more obvious than those in MOF survivors (t = 6.920 - 11. 665, P < 0.00). The LFI and LAR in MOF patients were positively related to leukocyte CD18 expression, sICAM-1, and sVCAM-1 concentration (r = 0.691 - 0.844, P < 0.001); LFI was positively related to LAR (r = 0.711, P < 0.001).

CONCLUSION

The abnormalities of leukocyte rheologic characteristics and CAMs might be closely related to the occurrence of MOF and the severity of pathologic changes.

[Allotransplantation of cultured fetal parathyroid gland cells in treating patients with hypoparathyroidism]

OBJECTIVE

To evaluate the therapeutic efficacy of transplantation of cultured human fetal parathyroid gland (chf-PTG) cells in treating patients with primary or secondary hypoparathyroidism.

METHODS

Chf-PTG cells were allotransplanted into the renal adipose capsules of 6 patients with hypoparathyroidism under the ultrasonic guidance. The levels of serum parathyroid hormone (PTH) and calcium were monitored by radioimmunometric assay (RIA) and biochemical method, respectively. Both indexes of pre-and post-operation were compared and the data were analyzed.

RESULTS

The levels of serum PTH and calcium were markedly elevated from three days to the first two weeks following transplantation of chf-PTG cells (P < 0.01). The PTH and calcium levels gradually stabilized from day 14 up to months 9-12, during which the symptoms of the patients alleviated or relieved.

CONCLUSION

The transplantation of chf-PTG cells is a potential method for treating patients with primary or secondary hypoparathyroidism.

[Study on alkaline hydrolysis of polyglutamate for de-esterification]

This paper reports the alkaline hydrolysis of poly(methyl glutamate), poly (benzyl glutamate) and copoly(methyl glutamate-benzyl glutamate-glutamic acid) for de-esterification. The results showed that in this process of alkaline hydrolysis the demethylation of poly(methyl glutamate) was faster, but debenzylation of poly(benzyl glutamate) was hardly processed. An increase in the methyl glutamate content of starting copolymers, in the alkaline concentration and the time of alkaline hydrolysis, and a decrease in the film thickness, would lead to a raise in the degree of alkaline hydrolysis, that is, an increase of the glutamic acid segment content in product of alkaline hydrolysis.

Ticlopidine-induced severe cholestatic hepatitis

We report a case study of an 86-year-old female patient with severe cholestatic hepatitis who was undergoing treatment with oral ticlopidine 250 mg daily for coronary artery disease. The patient had nausea and vomiting and was jaundiced after taking ticlopidine for 6 weeks. She was admitted to the hospital for further evaluation. Ultrasound and endoscopic retrograde cholangiopancreatography eliminated the presence of biliary obstruction. Results from a liver biopsy showed a histopathologic picture consistent with cholestatic hepatitis. Ticlopidine-induced cholestatic hepatitis has been reported 32 times in the foreign literature. This is the first reported severe cholestatic hepatitis (total bilirubin up to 43 mg/dl) case in Taiwan. Ticlopidine-related blood dyscrasia is a renowned adverse drug effect; liver function should be monitored in patients receiving ticlopidine therapy.

Increased nondisjunction of chromosome 21 with age in human peripheral lymphocytes

Fluorescence in situ hybridization (FISH) on binucleated cells with chromosome-specific DNA probes provides a convenient way to visualize reciprocal segregation patterns in daughter nuclei, and overcomes most problems related to the artefactual loss or gain of chromosomes that flaw chromosome preparations. In this study, FISH was employed to evaluate age- and sex-effects on spontaneous malsegregation, nondisjunction and loss of chromosome 21 in human lymphocytes after the first division in culture. A total of 68 healthy nonsmokers and nondrinkers of alcohol (37 males and 31 females) were grouped by age as Group I (0-10 years), Group II (20-30 years), Group III (40-50 years) and Group IV (60-70 years), with at least seven subjects per group and sex. FISH with a pericentric chromosome 21 specific DNA probe was carried out on binucleated lymphocytes, cytokinesis-blocked by cytochalasin B (6 microg/ml for 26 h) at 44 h after initiation of cultures. Linear regression analyses demonstrated a significant age-related increase in the frequency of micronuclei without chromosome 21 (MN-21)(r=0.73, p<0.001 in females; r=0.69, p<0.001 in males) in all binucleated cells, with a steeper slope in females (0.1758) than in males (0. 1241). Analysis using the 2x2 chi-square (chi(2)) test on the frequencies of MN-21 showed significant age-related differences in both males and females, except males in Group III and Group IV (p>0. 05). A significant sex-related difference was found only in subjects over 60 years (p<0.05), with females having more MN-21 (12.57 per thousand vs. 8.43 per thousand) than males. Loss of chromosome 21, occurring at mean levels of 0.38 per thousand in all binucleated cells and 0.24 per thousand in binucleated cells containing four FISH signals, was shown not to be age- or sex-related. A positive age-related increase in nondisjunction of chromosome 21 was shown in males (r=0.50, p<0.01), females (r=0.61, p<0.001) and all subjects (r=0.55, p<0.001) by linear regression analysis. An age effect was found only between children and adults (p<0.01 for females, p<0.05

NFATz: a novel rel similarity domain containing protein

Nuclear Factor of Activated T cell (NFAT) is a family of transcription factors that are important for the coordinate expression of various cytokines and immunoregulatory cell surface molecules in T cells and other types of cells in the immune system. In addition, analysis of gene disrupted mice revealed that some members of NFAT family are important for the development of myocardium, myocardial hypertrophy, and mesenchymal stem cells. NFAT family proteins have two conserved domains, the NFAT Homology Domain (NHD) and the Rel Similarity Domain (RSD). The RSD is DNA binding and AP-1 interacting domain which has structural similarity to the Rel Homology Region, the DNA binding domain of Rel family proteins. The NHD is a regulatory domain required for the Ca regulated translocation of NFAT. We report here the isolation and initial characterization of a novel RSD containing protein designated NFATz. NFATz has a RSD but no NHD. NFATz protein is localized in the nucleus without Ca signal. There is no detectable binding to a typical NFAT site even in the presence of AP-1, and it is not capable of activating transcription through the NFAT site. The chromosomal location determined by FISH revealed that NFATz and NFATx genes are in the same region.

[Effect of raw radish on pharmacological action of ginseng]

Ginseng decoction can increase the memory-improvement, weary-resistance, antihypoxia, sedation in mice, and increase the weight of spleen and accessory sexual gland, but reduce the weight of thymus. Raw radish can decrease these pharmacological effects in varying degrees, except the sedation.

Pulmonary artery perfusion with protective solution reduces lung injury after cardiopulmonary bypass

BACKGROUND

The inflammatory response and higher temperature of lung tissue during cardiopulmonary bypass can result in lung injury. This study was to evaluate the protective effect of pulmonary perfusion with hypothermic antiinflammatory solution on lung function after cardiopulmonary bypass.

METHODS

Twelve adult mongrel dogs were randomly divided into two groups. The procedure was carried out through a midline sternotomy, cardiopulmonary bypass was established using cannulas placed in the ascending aorta, superior vena cava, and right atrium near the entrance of the inferior vena cava. After the ascending aorta was clamped and cardioplegic solution infused, the right lung was perfused through a cannula placed in the right pulmonary artery with 4 degrees C lactated Ringer's solution in the control group (n = 6) and with 4 degrees C protective solution in the antiinflammation group (n = 6). Antiinflammatory solution consisted of anisodamine, L-arginine, aprotinin, glucose-insulin-potassium, and phosphate buffer. Plasma malondialdehyde, white blood cell counts, and lung function were measured at different time point before and after cardiopulmonary bypass; lung biopsies were also taken.

RESULTS

Peak airway pressure increased dramatically in the control group after cardiopulmonary bypass when compared with the antiinflammation group at four different time points (24 +/- 1, 25 +/- 2, 26 +/- 2, 27 +/- 2 cm H2O versus 17 +/- 2, 18 +/- 1, 17 +/- 1, 18 +/- 1 cm H2O; all p < 0.01). Pulmonary vascular resistance increased significantly in the control group than in the antiinflammation group at 5 and 60 minutes after cardiopulmonary bypass (1,282 +/- 62 dynes x s x cm(-5) versus 845 +/- 86 dynes x s x cm(-5) and 1,269 +/- 124 dynes x s x cm(-5) versus 852 +/- 149 dynes x s x cm(-5), p < 0.05). Right pulmonary venous oxygen tension (PvO2) in the antiinflammation group was higher than in the control group at 60 minutes after cardiopulmonary bypass (628 +/- 33.3 mm Hg versus 393 +/- 85.9 mm Hg, p < 0.05). The ratio of white blood cells in the right atrial and the right pulmonary venous blood was lower in the antiinflammation group than in the control group at 5 minutes after the clamp was removed (p < 0.05). Malondialdehyde were lower in the antiinflammation group at 5 and 90 minutes after the clamp was removed (p < 0.01 and p < 0.05, respectively). Histologic examination revealed that the left lung from both groups had marked intraalveolar edema and abundant intraalveolar neutrophils, whereas the right lung in the control group showed moderate injury and the antiinflammation group had normal pulmonary parenchyma.

CONCLUSIONS

Pulmonary artery perfusion using hypothermic protective solution can reduce lung injury after cardiopulmonary bypass.

The genome sequence of Drosophila melanogaster

The fly Drosophila melanogaster is one of the most intensively studied organisms in biology and serves as a model system for the investigation of many developmental and cellular processes common to higher eukaryotes, including humans. We have determined the nucleotide sequence of nearly all of the approximately 120-megabase euchromatic portion of the Drosophila genome using a whole-genome shotgun sequencing strategy supported by extensive clone-based sequence and a high-quality bacterial artificial chromosome physical map. Efforts are under way to close the remaining gaps; however, the sequence is of sufficient accuracy and contiguity to be declared substantially complete and to support an initial analysis of genome structure and preliminary gene annotation and interpretation. The genome encodes approximately 13,600 genes, somewhat fewer than the smaller Caenorhabditis elegans genome, but with comparable functional diversity.

[The influence of different root length on stress distribution in the bone around abutment root of telescopic overdenture]

OBJECTIVE

To investigate the influence of bone height around the roots on stress distribution in a mandible with two canines remained and covered with an telescopic overdenture.

METHODS

Three-dimensional finite element method.

RESULTS

As the height of the bone around the roots decreased, the stress increased. But the maximum stress in the bone in this study is lower than that in the bone around the canine under normal condition.

CONCLUSION

In the mandible, when the alveolar bone resorption reaches the apical 1/3 of canine (root length 4, 5 mm), if part of the tooth crown was removed, to make an acceptable crown/root ratio, so the canine can be used as the abutment of an overdenture.

Role of the TATA binding protein-transcription factor IIB interaction in supporting basal and activated transcription in plant cells

The TATA binding protein (TBP) and transcription factor IIB (TFIIB) play crucial roles in transcription of class II genes. The requirement for TBP-TFIIB interactions was evaluated in maize cells by introducing mutations into the Arabidopsis TBP (AtTBP2) within the C-terminal stirrup. Protein binding experiments indicated that amino acid residues E-144 and E-146 of AtTBP2 are both essential for TFIIB binding in vitro. Activation domains derived from herpes simplex viral protein VP16, the Drosophila fushi tarazu glutamine-rich domain (ftzQ), and yeast Gal4 were tested in transient assays. TBP-TFIIB interactions were dispensable for basal transcription but were required for activated transcription. In general, activated transcription was more severely inhibited by TBP mutation E-146R than by mutation E-144R. However, these TBP mutations had little effect on activity of the full-length cauliflower mosaic virus 35S and maize ubiquitin promoters, thus demonstrating that strong TBP-TFIIB contacts are not always required for transcription driven by complex promoters.

The regulation of caveolin expression and localization by serum and heparin in vascular smooth muscle cells

Caveolae have been implicated in growth factor receptor and G-protein coupled receptor signaling in vascular cells. It has been postulated that caveolin, the structural protein of caveolae, may act as a general tyrosine kinase inhibitor by binding and inhibiting signaling molecules involved in the activation of the MAP kinase proliferation cascade. Using an in vitro model of VSMC proliferation, we found that serum stimulation caused a dose dependent decrease in both caveolin-1 and caveolin-2 protein levels in human coronary artery smooth muscle cells. Heparin, an inhibitor of VSMC proliferation, inhibited the serum-induced loss of caveolin-1 and caveolin-2. In addition, heparin caused an increase in both caveolin-1 and caveolin-2 localization to caveolae-enriched sucrose gradient membrane fractions when compared to serum alone. Taken together, caveolin may play an important role in the regulation of VSMC proliferation and heparin and serum have opposing effects on caveolin expression and localization in VSMC.

Complementation between HLA-DR4 (DRB1*0401) and specific H2-A molecule in transgenic mice leads to collagen-induced arthritis

We generated transgenic mice with DRB1*0401 gene with mutation in the beta2 domain (aa 110 and 139) for better interaction with mCD4. The DR4 transgene was introduced into H2-Aq (B10RQB3) and H2-Af (B10RFB3) to examine the role of DR4 in collagen arthritis. The HLA-DR molecules in these mice were found to be functional on the basis of their positive/negative selection of the Vbeta T cell repertoire. H2-Aq mice are resistant to porcine CII-induced arthritis. The RQB3/DR4 mice (H2Aq/DR4) developed severe collagen induced arthritis (CIA) when immunized with Porcine type II collagen while the negative littermates were resistant. RQB3.DR4 mice were also highly susceptible to CIA induced by Human CII while negative littermates got only mild disease. However, RFB3/DR4 mice (H2Af/ DR4) did not get CIA with any type II collagen. Therefore, the DR4 gene in the context of H2-Aq predisposes to severe arthritis but not in the context of H2-Af. Antibodies to renatured cyanogen bromide (CB) cleaved fragments of PII in RQB3/DR4 mice and negative littermates suggest that the presence of DR4 does not result in any differences in specificity of antibody response to CB fragments. These results indicate that a specific gene complementation occurring between DR4 and H2.Aq but not DR4 and H2Af promotes the induction of arthritis with PII and HII in these mice. A similar interaction may be involved between DR and DQ molecules in human RA.

Specific interactions with TBP and TFIIB in vitro suggest that 14-3-3 proteins may participate in the regulation of transcription when part of a DNA binding complex

The 14-3-3 family of multifunctional proteins is highly conserved among animals, plants, and yeast. Several studies have shown that these proteins are associated with a G-box DNA binding complex and are present in the nucleus in several plant and animal species. In this study, 14-3-3 proteins are shown to bind the TATA box binding protein (TBP), transcription factor IIB (TFIIB), and the human TBP-associated factor hTAF(II)32 in vitro but not hTAF(II)55. The interactions with TBP and TFIIB were highly specific, requiring amino acid residues in the box 1 domain of the 14-3-3 protein. These interactions do not require formation of the 14-3-3 dimer and are not dependent on known 14-3-3 recognition motifs containing phosphoserine. The 14-3-3-TFIIB interaction appears to occur within the same domain of TFIIB that binds the human herpes simplex virus transcriptional activator VP16, because VP16 and 14-3-3 were able to compete for interaction with TFIIB in vitro. In a plant transient expression system, 14-3-3 was able to activate GAL4-dependent beta-glucuronidase reporter gene expression at low levels when translationally fused with the GAL4 DNA binding domain. The in vitro binding with general transcription factors TBP and TFIIB together with its nuclear location provide evidence supporting a role for 14-3-3 proteins as transcriptional activators or coactivators when part of a DNA binding complex.

MRI evaluation of bone marrow of normal lumbar vertebra in the Chinese: normal patterns and preliminary quantitative study

OBJECTIVES

To establish the normal patterns of lumbar vertebral marrow in normal Chinese, to determine its normal value of relaxation times (T1 and T2), and to investigate the relationship between relaxation time and age or sex.

METHODS

320 of 1000 cases (sampled randomly) received MR imaging. According to the MRI findings of sagittal T1WI, marrow patterns were established. 268 cases were studied quantitatively (T1 and T2 measurements).

RESULTS

The normal bone marrow patterns of lumbar vertebra were divided into four main patterns (six subgroups). The normal values of relaxation times (T1 and T2) were measured. T1 or T2 value decreased with aging. No significant difference in T1 value between two sexes (< 40 years old: u = 0.4307, P > 0.50; > or = 40 years old: u = 0.554, P > 0.05). No significant difference was seen in T2 value between two sexes before 40 years old (u = 1.3628, P > 0.10), but significant difference after 40 years old (u = 2.1498, P < 0.05).

CONCLUSIONS

To establish the normal patterns of lumbar vertebral marrow and determine its normal values of relaxation times have important clinical value in the diagnosis of bone marrow diseases.

A logit analysis of the likelihood of leaving rural settings for registered nurses

This study examined the net effects of individual and community factors on the likelihood of registered nurses leaving current jobs using a logit analysis. Based on data from a survey of 2,509 rural nurses, four separate models were estimated and compared: one for nurses in rural settings as a whole and the other three for nurses in hospitals, skilled nursing facilities, and community/public health agencies. Results of the general model indicated that nurses' marital status, age, position, income, job satisfaction, and satisfaction with the community were significant determinants of the likelihood of leaving current jobs. Job satisfaction was the most significant factor, followed by satisfaction with the community. Findings from the models for three different employment settings were similar to those of the general model. However, the significance of factors and their strength of effect on nurses' decisions to leave or stay in their current jobs differed across the three types of facilities. Based on these findings rural nursing administrators and policy-makers should give priority to retention strategies that focus on improving the job environment. The development of different strategies for different groups of nurses (i.e., by age or marital status) and different types of facilities should increase the benefit/cost ratio. In addition, programs that involve rural health care agencies in community and economic development should be further explored as an avenue to increased nurse retention in rural areas.

Predicting the degree of rurality of physician assistant practice location

This study used a block multiple regression analysis to examine the impacts of different factors on the degree of rurality of physician assistants' (PAs') practice location and compared the power of each block of factors in predicting rurality. Differences in the models for PAs in primary care specialties and for PAs as a whole were also explored. The findings suggest that policies should provide support to PA students in primary care specialties and to rural-oriented PA education/training programs. Efforts to facilitate PA recruitment and retention should include, among other things, increasing practice responsibility/autonomy, broadening acceptance of PA prescriptive authority, and providing equitable reimbursement for nonphysician care of Medicare and Medicaid beneficiaries.

Returns to nursing education: rural and nonrural practice

This study uses data from a national sample of registered nurses to compare earnings of nurses in rural and nonrural practice. The comparisons, conditioned by the nurses' education level, are analogous to the concept of "returns to human capital investment" used in labor economics. A general linear model is applied within a framework of labor economics analysis. Results show that nurses with more education receive less for their investment if they practice in rural areas. Work experience and employment setting are also related to lower annualized earnings for rural practice. One exception to the otherwise consistent findings is that returns to advanced practice nursing are higher in rural areas. Results and policy implications are discussed.

[Influence of aging and sex on chromosome 21 segregation in human lymphocytes]

OBJECTIVE

To determine the influence of aging and sex on the segregation of chromosome 21.

METHODS

Lymphocytes were obtained from healthy donors of different ages, both sexes, and were treated with cytochalasin B. Binucleated cells were hybridized with chromosome 21 specific probe, and simultaneously, chromosome 21 loss and non-disjunction were detected.

RESULTS

The coefficients of correlation between age and binucleated cells containing 4, 2 and 6 signals were -0.35(P<0.01), 0.18 and 0.38(P<0.01) respectively. The coefficients of correlation between age and nondisjunction of chromosome 21 and micronuclei were 0.56(P<0.01) and 0.70(P<0.01) respectively.

CONCLUSION

There is a significant increase with age in the number of micronuclei and missegregation. Nondisjunction of chromosome 21 is much more frequent than loss in vivo and in vitro. No significant difference in nondisjunctioin between male and female was noted. Age effect is more significant in female than in male.

Effect of liposome-encapsulated total alkaloid of harmaline on rabbit lens epithelial cells: experimental study on the prevention of posterior capsule opacification

PURPOSE

To investigate whether liposome encapsulated total alkaloid of Harmaline (TAH) as a therapeutic agent is beneficial to prevention of posterior capsular opacification (PCO).

METHODS

Liposome-encapsulated TAH was prepared by modified freeze-thawing method. 0.1 ml of liposome-encapsulated TAH (0.2 mg/ml) was injected into the capsular bag during extracapsular lens extraction (ECLE) of each eye in total 10 rabbit eyes. Blank liposome or balance salt solution (BSS) was used as control. Slit-lamp examination and histopathological examination was used to evaluated capsule opacification. Intraocular pressure (IOP), density and morphology of corneal endothelia cells, the amplitude and latency of b wave of ERG were measured.

RESULTS

The inflammatory response was mild both in TAH treated and the control group. PCO formation occurred in the control group 2 weeks postoperatively, but the posterior capsule was clear in TAH treated eyes. 4 weeks and 8 weeks after operation, PCO occurred both in TAH treated and control eyes. However, it was milder in the TAH treated eyes. IOP remained at the normal level in all eyes. There was no difference in the density of corneal endothelial cells, and the amplitude and latency of b wave of ERG between TAH treated and control eyes. Histopathological study revealed that lens epithelial proliferation occurred 4 weeks and the Soemmerings ring developed 8 weeks postoperatively in the control eyes. However, only mild vacuolization and pkynotic changes of lens epithelial cells were found in TAH treated eyes. Transmmission electronic microscopy demonstrated that there were mild cytoplasm vacuolization and mitochondria swelling of lens epithelial cells in TAH treated eyes.

CONCLUSION

The results suggest that liposome encapsulated TAH can inhibit metaplasia and proliferation of lens epithelial cells in the rabbit eye without obvious toxicity to the eye tissue. It may be used as a potential agent to prevent the development of PCO.

Distribution of human lens crystallins and their sulphydryl contents of different age in two-dimension electrophoresis

PURPOSE

To analyze water-soluble (WS) human lens proteins of fetus, adult and age-related cataract by two-dimensional IEF/SDS-PAGE electrophoresis.

METHODS

DACM [N-(7-Dimethylamino-4-methyl-3-coumarinyl) maleimide] was used to determine the lens proteins sulphydryl (SH) content.

RESULT

Protein SH contents in WS lens proteins have no significant difference among fetus, adult and age-related cataract lens. This is different from the relative published results obtained in lens proteins of animal cataract model using similar SH detecting methods.

CONCLUSIONS

IEF/SDS-PAGE electrophoresis demonstrated that there were much more fragmentation of crystallins during lens development and cataractogenic process. It is suggested that this phenomenon is likely to be due to further conformational changes in the fragmented cyrstallins during aging and cataractogenic process.

Three-dimensional finite element analysis and comparison of stress distribution in overdentures supported with bar attachments and telescopic crowns

OBJECTIVE

To determine which one of the overdenture (OD) retainers was more beneficial to the abutments--the bar or the telescopic crown--and if a tooth could be used as an OD abutment when the supporting bone decreased to half of the root.

MATERIALS AND METHODS

The three-dimensional finite element method was used to investigate the stress distribution in a mandible with an overdenture supported by the roots of two canines. The two teeth were either connected with a bar attachment or restored with telescopic crowns, and were then restored with a complete overdenture. For each type of superstructure, the influence of bone height around the roots (no alveolar resorption and resorption to half of the root length) was analyzed under three loading conditions.

RESULTS

The most extreme stress values were located at the alveolar ridge crest of the bone around the root of the abutment. In the case of anterior loading, the largest compressive stress (LCS) in telescopic crown overdenture (TOD) was lower. When loaded posteriorly there was no obvious difference between bar attachment overdenture (BOD) and TOD. At the alveolar ridge crest around the root of the abutment, the stress value in the model with decreased bone level was higher than in the model with normal bone level, but the range was not significant.

CONCLUSION

1. In terms of stress in the alveolar bone, complete overdenture over telescopic crowns is more convenient than over bar attachments. 2. Stress increases as the height of the bone around the roots decreases, but the increment is less than 30%. It is important for an abutment with bone resorption to perform root amputation to obtain an acceptable crown/root ratio.

Ferrocene-conjugated m-phenylenediamine conducting polymer-incorporated peroxidase biosensors

The development and characteristics of a reagentless amperometric biosensor employing horseradish peroxidase incorporated in an electrochemically deposited ferrocene-modified phenylenediamine film on a glassy carbon electrode is reported. The horseradish peroxidase/poly(m-aminoanilinomethylferrocene)- modified glassy carbon electrode reagentless biosensor measured hydrogen peroxide and other organic peroxides in both aqueous and organic medium by reduction at a low applied potential of -0.05 V (vs Ag/AgCl) without interference from molecular oxygen. When modified with glucose oxidase, the new bienzyme electrode measured glucose sensitively and selectively, demonstrating the suitability of the above peroxide biosensor for other oxidoreductase enzyme-based biosensors.

Fiber-optic enzyme biosensor for direct determination of organophosphate nerve agents

A fiber-optic enzyme biosensor for the direct measurement of organophosphate nerve agents was developed. The basic element of this biosensor is organophosphorus hydrolase immobilized on a nylon membrane and attached to the common end of a bifurcated optical fiber bundle. The enzyme catalyzes the hydrolysis of organophosphate compounds to form stoichiometric amounts of chromophoric products that absorb light at specific wavelengths. The back-scattered radiation of the specific incident radiation was measured using a photomultiplier detector and correlated to the organophosphate concentration. The effects of buffer pH, temperature, and the units of enzyme immobilized on the steady-state and kinetic response of the biosensor were investigated to optimize the operating conditions for the fiber-optic enzyme biosensor. These conditions were then used to measure parathion, paraoxon, and coumaphos selectively without interference from carbamates and triazines. Concentrations as low as 2 microM can be measured in less than 2 min using the kinetic response. When stored in buffer at 4 degreesC the biosensor shows long-term stability.